Re: [PATCH 2/2] platform/x86: intel_pmc_core: Allow to dump debug registers on S0ix failure

From: Rajat Jain
Date: Mon Mar 18 2019 - 11:13:16 EST

On Sat, Mar 16, 2019 at 1:43 AM Rajneesh Bhardwaj
<rajneesh.bhardwaj@xxxxxxxxx> wrote:
>
> On Wed, Mar 13, 2019 at 03:21:24PM -0700, Rajat Jain wrote:
> > Add a module parameter which when enabled, will check on resume, if the
> > last S0ix attempt was successful. If not, the driver would provide
> > helpful debug information (which gets latched during the failed suspend
> > attempt) to debug the S0ix failure.
>
> + Srinivas and David.
>
> >
> > This information is very useful to debug S0ix failures. Specially since
> > the latched debug information will be lost (over-written) if the system
> > attempts to go into runtime (or imminent) S0ix again after that failed
> > suspend attempt.
> >
> > Signed-off-by: Rajat Jain <rajatja@xxxxxxxxxx>
> > ---
> > drivers/platform/x86/intel_pmc_core.c | 86 +++++++++++++++++++++++++++
> > drivers/platform/x86/intel_pmc_core.h | 7 +++
> > 2 files changed, 93 insertions(+)
> >
> > diff --git a/drivers/platform/x86/intel_pmc_core.c b/drivers/platform/x86/intel_pmc_core.c
> > index 55578d07610c..b1f4405a27ce 100644
> > --- a/drivers/platform/x86/intel_pmc_core.c
> > +++ b/drivers/platform/x86/intel_pmc_core.c
> > @@ -20,6 +20,7 @@
> > #include <linux/module.h>
> > #include <linux/pci.h>
> > #include <linux/platform_device.h>
> > +#include <linux/suspend.h>
> > #include <linux/uaccess.h>
> >
> > #include <asm/cpu_device_id.h>
> > @@ -890,9 +891,94 @@ static int pmc_core_remove(struct platform_device *pdev)
> > return 0;
> > }
> >
> > +#ifdef CONFIG_PM_SLEEP
> > +
> > +static bool warn_on_s0ix_failures;
> > +module_param(warn_on_s0ix_failures, bool, 0644);
> > +MODULE_PARM_DESC(warn_on_s0ix_failures, "Check and warn for S0ix failures");
> > +
> > +static int pmc_core_suspend(struct device *dev)
> > +{
> > + struct pmc_dev *pmcdev = dev_get_drvdata(dev);
> > +
> > + /* Save PC10 and S0ix residency for checking later */
> > + if (warn_on_s0ix_failures &&
> > + !rdmsrl_safe(MSR_PKG_C10_RESIDENCY, &pmcdev->pc10_counter) &&
> > + !pmc_core_dev_state_get(pmcdev, &pmcdev->s0ix_counter))
> > + pmcdev->check_counters = true;
> > + else
> > + pmcdev->check_counters = false;
> > +
> > + return 0;
> > +}
> > +
> > +static inline bool pc10_failed(struct pmc_dev *pmcdev)
> > +{
> > + u64 pc10_counter;
> > +
> > + if (!rdmsrl_safe(MSR_PKG_C10_RESIDENCY, &pc10_counter) &&
> > + pc10_counter == pmcdev->pc10_counter)
> > + return true;
> > + else
> > + return false;
> > +}
> > +
> > +static inline bool s0ix_failed(struct pmc_dev *pmcdev)
> > +{
> > + u64 s0ix_counter;
> > +
> > + if (!pmc_core_dev_state_get(pmcdev, &s0ix_counter) &&
> > + s0ix_counter == pmcdev->s0ix_counter)
> > + return true;
> > + else
> > + return false;
> > +}
> > +
> > +static int pmc_core_resume(struct device *dev)
> > +{
> > + struct pmc_dev *pmcdev = dev_get_drvdata(dev);
> > +
> > + if (!pmcdev->check_counters)
> > + return 0;
> > +
> > + if (pc10_failed(pmcdev)) {
> > + dev_info(dev, "PC10 entry had failed (PC10 cnt=0x%llx)\n",
> > + pmcdev->pc10_counter);
> > + } else if (s0ix_failed(pmcdev)) {
> > +
> > + const struct pmc_bit_map **maps = pmcdev->map->slps0_dbg_maps;
>
> slps0_dbg feature is not available on Skylake and Kabylake. PCH IP power
> gating status is available on all.

Right, so the slps0_dbg_maps field is only populated for the platforms
that have the slps0_dbg feature. So it seems like the below code would
work well for both kind of platforms.

>
> > + const struct pmc_bit_map *map;
> > + int offset = pmcdev->map->slps0_dbg_offset;
> > + u32 data;
> > +
> > + dev_warn(dev, "S0ix entry had failed (S0ix cnt=%llu)\n",
> > + pmcdev->s0ix_counter);
>
> I feel this dev_warn may be frowned upon and should be possible kept behind
> something like pm_debug_messages_on though module param helps mitigate it.

Right, in my mind, as the parameter name suggests, the whole intent of
the "warn_on_s0ix_failures" is to generate noticable warnings. Since
these warnings are off by default, and thus will only be generated
some one turns on the parameter, thus indicating he is interested in
being warned for failures.

Thanks,

Rajat

>
> > + while (*maps) {
> > + map = *maps;
> > + data = pmc_core_reg_read(pmcdev, offset);
> > + offset += 4;
> > + while (map->name) {
> > + dev_warn(dev, "SLP_S0_DBG: %-32s\tState: %s\n",
> > + map->name,
> > + data & map->bit_mask ? "Yes" : "No");
> > + ++map;
> > + }
> > + ++maps;
> > + }
> > + }
> > + return 0;
> > +}
> > +
> > +#endif
> > +
> > +const struct dev_pm_ops pmc_core_pm_ops = {
> > + SET_LATE_SYSTEM_SLEEP_PM_OPS(pmc_core_suspend, pmc_core_resume)
> > +};
> > +
> > static struct platform_driver pmc_core_driver = {
> > .driver = {
> > .name = "pmc_core",
> > + .pm = &pmc_core_pm_ops
> > },
> > .probe = pmc_core_probe,
> > .remove = pmc_core_remove,
> > diff --git a/drivers/platform/x86/intel_pmc_core.h b/drivers/platform/x86/intel_pmc_core.h
> > index 88d9c0653a5f..fdee5772e532 100644
> > --- a/drivers/platform/x86/intel_pmc_core.h
> > +++ b/drivers/platform/x86/intel_pmc_core.h
> > @@ -241,6 +241,9 @@ struct pmc_reg_map {
> > * @pmc_xram_read_bit: flag to indicate whether PMC XRAM shadow registers
> > * used to read MPHY PG and PLL status are available
> > * @mutex_lock: mutex to complete one transcation
> > + * @check_counters: On resume, check if counters are getting incremented
> > + * @pc10_counter: PC10 residency counter
> > + * @s0ix_counter: S0ix residency (step adjusted)
> > *
> > * pmc_dev contains info about power management controller device.
> > */
> > @@ -253,6 +256,10 @@ struct pmc_dev {
> > #endif /* CONFIG_DEBUG_FS */
> > int pmc_xram_read_bit;
> > struct mutex lock; /* generic mutex lock for PMC Core */
> > +
> > + bool check_counters; /* Check for counter increments on resume */
> > + u64 pc10_counter;
> > + u64 s0ix_counter;
> > };
> >
> > #endif /* PMC_CORE_H */
> > --
> > 2.21.0.360.g471c308f928-goog
> >
>
> --
> Best Regards,
> Rajneesh